1. Field of the Invention
The present invention relates to an antivibration device for correcting a hand shake, and particularly to an antivibration device which is used in a photographing apparatus, such as a camera, for detecting a hand shake occurring in a photographing operation and correcting the hand shake by moving a part of the photographing optical system.
2. Related Background Art
The hand shake occurs when the photographer holds the photographing apparatus by his or her hand to take a picture. The hand shake spoils the quality of the picture to be taken. The hand shake is liable to occur especially when a lens having a long focal length is used, or when the shutter speed of the lens is slow.
FIG. 7 is a view for explaining the whole structure of an ordinary antivibration device according to the conventional art.
Referring to FIG. 7, reference numeral 31 denotes an interchangeable lens system, and 32 a camera body. The optical system of the interchangeable lens 31 is comprised of a fixed lens group L11, a focusing lens group L12 which moves in the direction of the optical axis I to perform a focusing operation, and a shake correcting lens group L13 (shake correcting optical system) which shifts in a direction substantially perpendicular to the direction of the optical axis I to correct a shake.
A shake directing unit 33 is comprised of a velocity sensor, or an angular velocity sensor, etc., so as to output a shake detection signal in response to a detected vibration in the direction perpendicular to the optical axis of the camera. This shake detecting unit 33 is provided within the interchangeable lens system 31 in FIG. 7. The shake correcting unit 34 constitutes a shift mechanism so as to shift the shake correcting lens group L13 on a plane substantially perpendicular to the optical axis I.
The shake control unit 35 is provided within the interchangeable lens system 31, and has a memory portion which stores lens information on focal length or the like and information related to the shake correction. The shake control unit 35 controls drive of the shake correcting unit 34 on the basis of the information stored in said memory portion and an output from the shake detecting unit 33 mentioned above so as to perform the shake correction.
The antivibration device requires a predetermined space in order to secure a range for correction (a shift range) of the shake correcting lens group L13. For an antivibration device of the conventional type, there is a possibility of dust, etc., entering the blur correcting unit 34 from such space. Dust, etc., enter this space, for example, when accessories to the camera, such as a photographing lens, are interchanged in a photographing apparatus of an interchangeable type, such as a single lens reflex camera, or when films, or the like, are exchanged in a photographing apparatus of a non-interchangeable type, such as a lens shutter camera. When dust or the like enters, any of the driving units may be damaged.
In Japanese Patent Application Laid-Open No. 6-3727, there was disclosed an image shake correction apparatus with a lens supporting frame for supporting a correction optical system, and a light-shielding member for shielding from light a space generated between said lens supporting frame and a fixed frame which movably supports said lens supporting frame on a plane perpendicular to the photographing optical axis. However, since this light-shielding member was arranged to prevent leakage of light from the front side of the optical axis, the dust, etc., entering from the rear side of the optical axis, as mentioned above, could not be prevented.